During the fabrication of certain types of semiconductor devices, a gate stack may be formed on the surface of a semiconductor body. The area of the semiconductor body that lies below the gate stack defines a selectively conductive channel region. Various conductive regions in the semiconductor device may be formed by the implantation of one or more dopants into the layers of the semiconductor device. For example, a dopant may be implanted within the semiconductor body on either side of the gate stack to form source and drain regions. Additionally, a dopant may be implanted into and diffused through the gate stack to improve the conductivity of the gate stack. Specifically, the dopant migrates through the gate stack in a substantially vertical direction toward an interface within the gate stack. As semiconductor manufacturers continue to reduce the scale of semiconductor devices, however, the diffusion of dopants through the gate stack becomes more difficult. Where the concentration of dopant at the desired interface is too low, the reliability of the gate stack as a conductor may be reduced and the ability of the gate stack to control the conductivity of the channel can be impeded.